One thing he always makes time for, no matter what? Showering. He once told Reddit it was his most important daily habit.

Once he's up, Musk launches into a blistering schedule that breaks his time into a series of five-minute slots. The entrepreneur has been known to work 85 to 100 hours a week, and he estimates that 80% of his time at work is spent on engineering and design.

No two days are the same for Musk. He spends Mondays and Fridays at SpaceX in Los Angeles. On Tuesdays, Wednesdays, and Thursdays, he heads to the Bay Area to work at Tesla. Quartz estimates that he spends an average of 42 hours a week working at Tesla and 40 hours a week working at SpaceX. He also told Y Combinator that he usually spent about half a day working at the artificial intelligence nonprofit OpenAI.

On the weekends, it's more of a toss-up. Sundays are usually spent traveling or staying at his Bel Air mansion. On Saturday, he either works at SpaceX ...

... or spends time with his five young sons. Speaking about his kids in 2013, he said: "What I find is I'm able to be with them and still be on email. I can be with them and still be working at the same time ... If I didn't, I wouldn't be able to get my job done."

He ends up getting most of his calories later in the day. "Business dinners are probably where I eat way too much," he told Auto Bild.

When it comes to food, one of his favorites is Diet Coke, thanks to "some infernal ingredient." Musk told Auto Bild that he had since cut back on the soda. CBS previously reported on the tech mogul's preference for French food, barbecue, and whiskey.

To stay in shape, Musk usually hits the gym about once or twice a week.

Despite his busy life, he also carves out enough time to read. Some of his favorite titles include the fantasy classic "The Lord of the Rings," biographies of innovators like Benjamin Franklin and Albert Einstein, and an obscure 87-year-old history book on adventurers called "Twelve Against the Gods."

Musk may be a bookworm, but that doesn't mean he can't party. The entrepreneur's legendary bashes have included a birthday party at an English castle that turned into a big game of hide-and-seek, and inviting a knife-thrower to pop balloons that he held between his legs.

When all is said and done, Musk usually doesn't crash until 1 a.m. That late bedtime isn't too surprising for a man who's busy trying to do things like revolutionize the way we drive and send humans to Mars.